catenanes – Chemical Crystallography

Structure of the Month – May 2012

May 012012

Presented by: Nicholas G. White
Research Leader: Prof. Paul D. Beer
Published: Chemical Communications

Pyridinium-3,5-bis(triazole) can bind anions through polarised C-H···anion hydrogen bonds. We have incorporated this motif into pseudorotaxanes, catenanes and rotaxanes (in conjunction with an isophthalamide macrocycle), and the resulting interlocked architectures are formed in high yields and display interesting and unusual anion selectivities. Despite the difficulties of crystallising such systems, single crystals of a pseudorotaxane, rotaxane and catenane have all been isolated (as chloride salts). Data were collected using a Nonius Kappa-CCD, synchrotron radiation on I19 at Diamond and Cu Kα radiation with an Oxford Diffraction (Agilent) SuperNova (respectively). All three datasets are of unusually high quality for such systems (final R1 [I > 2σ(I)] = 6.9-8.0%).

Structure of the Month – May 2012

Diamond Light Source Annual Review

Jun 032011

The 2011 Diamond Annual Review, which highlights some of the world-class research recently undertaken at Diamond Light Source is now available from their website. The report includes a contribution from Prof. Paul Beer covering some of the fascinating interlocked structures determined from data collected using the Small Molecule Beamline, I19, as part of the Oxford Block Allocation Group (BAG). Highlights of their work include a novel halogen bonded rotaxane and the first reported crystal structure of a “handcuff catenane”.

Structure of a handcuff catenane

Structure of the Month – January 2011

Jan 012011

Presented by: Nicholas H. Evans & Christopher J. Serpell
Research Leader: Prof. Paul D. Beer
Published: Angewandte Chemie International Edition

Catenanes and rotaxanes are highly attractive targets for the supramolecular chemist due to their potential uses as molecular machines or as selective hosts for ionic and molecular guests. This molecule was synthesised via chloride anion templation and crystals grown by slow diffusion of diisopropyl ether into a chloroform/catenane solution. Data were collected on I19 at Diamond. This first handcuff catenane structure provided proof of the topology, also revealing potential further uses: the degree of slack in the large macrocycle could allow controlled rotation within the handcuff, and the large number of oxygen atoms in the cavity formed by the handcuff linker and large macrocycle could be used to bind cations.

Structure of the Month - January 2011